1. Field of the Invention
The present invention relates to an implantable insert for replacement fo anterior portions of vertabrae.
2. Description of the Prior Art
Anterior spine braces have been used for spinal column support. Such devices are sold by Zimmer, Inc. of Warsaw, Ind. USA, and are disclosed in the publication "Instrumentation for the Anterior Spine" by Harry K. Dunn, M.D. The brace comprises a bridge member that will span an injured vertebra or the void left, if it has been removed, by attaching supports above and below the damaged vertebra on the exterior of the spine. The supports are then screwed into place and are connected by one or more rods which provide compression carrying ability across the injured vertebra. A similar device is used for treatment of congenital scoliosis, and in each instance the brace that is utilized protrudes to the exterior of the spinal column. While the system is useful for treating certain problems, its installation and adjustment are difficult and it intrudes into the body cavity.
There have been various prostheses for spinal corrections and the like described in the patented art as well. A general type of brace which clamps onto the spinal column for correction of scoliosis is shown in U.S. Pat. No. 4,361,141. The patent discloses use of exterior rods which provide traction for the spinal column for straightening the spine. This device is not for replacement or support of an individual vertebra. A similar spinal column prosthesis utilizing exterior clamping mechanisms is shown in U.S. Pat. No. 4,085,744.
U.S. Pat. No. 4,422,451 also shows a spinal compression and distraction device which includes a type of a clip that hooks onto the spinal column and which will receive a rod for applying either distraction or compression loads to the spinal column, depending on the problem being treated.
U.S. Pat. No. 4,433,677 illustrates a device that is implantable, and forms a splint that is anchored in the pelvis and has upwardly extending rods that engage the spinal column to provide a spinal column support. This type of device, again, is on the exterior of the spine, which causes problems for the patient.
U.S. Pat. No. 3,867,728 shows a spinal repair prosthesis which replaces an injured disc between vertebrae. It has no fastening, other than normal ingrowth of tissue after it has been inserted in between two vertebrae.
A similar disc prosthesis is shown in U.S. Pat. No. 4,349,921 which again is for replacing a disc between two vertebrae and which is made so that it will conform to adjacent vertebral surfaces.